1. Field of the Invention
The present invention relates to a light source module for emitting a light beam and a technical field to perform a beam direct-writing on e.g., a semiconductor substrate, a glass substrate, a printing plate or the like with light beams by using a plurality of light source modules.
2. Description of the Background Art
As a light source module used for beam direct-writing to a semiconductor substrate, glass substrate, a printing plate or the like, conventionally, combination of a semiconductor laser of CAN package and a collimator lens has been well known, and for example, light source modules each having a structure in which a collimator lens is provided instead of a glass window of the CAN package serving as an outlet of light beams, being attached to a member for mounting, have been used. Thus, with regard to the light source module, pins standing at the member for mounting are inserted into holes of a holder in the CAN package to make positioning of the light source module and a reference surface of the holder is brought into contact with the member for mounting to determine the direction of the light beam to be emitted.
Japanese Patent Application Laid Open Gazette No. 6-47954 (Reference Document 1) discloses a structure in which a semiconductor laser of CAN package is provided on one side of a hole formed in a light source mounting stay which is part of a light source unit and a collimator lens is disposed inside the hole. The Reference Document 1 proposes a light source unit in which a plurality of light source modules each having such a structure are arranged.
In such a light source unit having a plurality of light source modules as shown in the Reference Document 1, however, it is necessary to determine respective outgoing positions and outgoing angles of a plurality of light beams to be uniform with high accuracy. When the semiconductor laser of the CAN package is used as a light source, since the semiconductor laser is supplied with power by, e.g., directly soldering wires to electric terminals protruding from the CAN package, there is a possibility that the outgoing position and the outgoing angle of a light beam which have been already determined in this stage may shift.
There is also a possibility that due to ill effects such as oscillation and heat in use of the light source unit, the outgoing positions and the outgoing angles of light beams may change with time to cause shifts from the original positions and angles in a stage where the light source unit is manufactured.
In a pattern writing apparatus (including an image recording apparatus), conventionally, a technique to improve a writing speed by using a light source array in which light sources for emitting a plurality of light beams for writing are arranged. In a scan type image recording apparatus using a drum, for example, a high-speed image recording to a photosensitive material is achieved by rotating the drum wound with the photosensitive material at high speed while moving the light source array for emitting a plurality of light beams which is provided in a two-dimensional arrangement in a subscan direction perpendicular to a direction of rotating the drum (main scan direction).
In an optical transmission line used for optical communication, in order to connect two bundles of optical fibers to each other, a technique to collectively connect a lot of optical fibers with efficiency is used where a plurality of optical fibers are two-dimensionally arranged on and connected to connectors and the connectors are connected to one another.
On such an array structure of a plurality of optical device elements, various techniques are disclosed. Japanese Patent Application Laid Open Gazette No. 11-177181 (Reference Document 2), for example, discloses a technique to control ON/OFF and intensity of light beams from a plurality of semiconductor lasers by arranging the semiconductor lasers to be electrically insulated from one another and wired on a side opposite to laser emission surfaces.
The above-discussed Reference Document 1 discloses a technique to ensure size-reduction of a light source unit for emitting a plurality of light beams, with a simplified structure in which positioning pins standing on a base block are inserted into pin holes of a light source member having a plurality of semiconductor lasers. Japanese Patent Application Laid Open Gazette No. 2000-335009 (Reference Document 3) discloses a technique to form a two-dimensional optical element aggregate of high precision, where optical element blocks on which a plurality of light emitting diodes for emitting light beams are positioned with high accuracy are supported by comb-teeth parts of a supporting member.
As to such an array structure of a plurality of optical device elements, it is important to ensure a high-precision arrangement. If the optical device element is a light source such as a semiconductor laser, it is necessary to determine respective outgoing positions and outgoing angles of a plurality of light beams to be aligned and uniform with high accuracy.
In the light source unit of Reference Document 1, for example, though positioning of the light source member having a plurality of semiconductor lasers is determined with high accuracy by using the positioning pins and the pin holes, in the case where the light source member is made of an insulating material, processings such as wire electro-discharge machining (or etching) and the like can not be performed and this makes it hard to form the pin holes with high accuracy. Especially, it becomes hard to determine the intervals of the pin holes with high accuracy in forming a plurality of pin holes.
In the optical element aggregate of Reference Document 3, though relative positions of a plurality of optical element blocks are determined by inserting the optical element blocks into the comb-teeth parts having grooves formed with high accuracy and the outgoing positions of light beams in a direction orthogonal to an arrangement direction of the light emitting diodes are determined with high accuracy by using a rod lens, it is impossible to correct the positions of the light emitting diodes in the arrangement direction. Further, since the optical element block has a structure in which a plurality of light emitting diodes are directly mounted on one substrate, it is difficult to use a light source of less reliability, such as a semiconductor laser (which has a possibility that some deficits may be found in screening due to aging or the like).